Oval Steam Turbine Casing

Abstract

A steam turbine may include a casing defining an interior cavity, wherein the casing comprises a first casing half and a second casing half, which are connected to one another to form the casing, wherein an interior surface of the first casing half has a first portion with a first curvature and a second portion with a second curvature, wherein the first curvature and the second curvature are different, and wherein an interior surface of the second casing half has a first portion with a first curvature and a second portion with a second curvature, wherein the first curvature and the second curvature are different. An interior surface of the casing may have a substantially oval-shaped cross-section. Internal pressure acting on the oval interior surface allows better sealing at the split line.

The invention claimed is: 
     
         1 . A steam turbine, comprising:
 a casing defining an interior cavity,   wherein the casing comprises a first casing half and a second casing half, which are connected to one another to form the casing,   wherein an interior surface of the first casing half has a first portion with a first curvature and a second portion with a second curvature, wherein the first curvature and the second curvature are different, and   wherein an interior surface of the second casing half has a first portion with a first curvature and a second portion with a second curvature, wherein the first curvature and the second curvature are different.   
     
     
         2 . The steam turbine of  claim 1 , wherein the first casing half and the second casing half are connected at a split line. 
     
     
         3 . The steam turbine of  claim 1 , wherein the first casing half and the second casing half are mechanically connected to one another. 
     
     
         4 . The steam turbine of  claim 2 , wherein, at the split line, an internal pressure causes flat edges of each of the first casing half and the second casing half to rotate towards one another to create a seal. 
     
     
         5 . The steam turbine of  claim 1 , wherein the inner surfaces of the first casing half and the second casing half comprise at least one flat portion corresponding to the first portion and a substantially curved portion corresponding to the second portion. 
     
     
         6 . The steam turbine of  claim 1 , wherein the first and second casing halves are separable from one another when not connected to one another. 
     
     
         7 . The steam turbine of  claim 1 , wherein the inner surfaces of the first casing half and the second casing half comprise a first flat portion, a second flat portion, and a substantially curved portion. 
     
     
         8 . The steam turbine of  claim 7 , wherein the substantially curved portion of the first and second casing halves is positioned between the first flat portion and the second flat portion. 
     
     
         9 . The steam turbine of  claim 7 , wherein the first flat portions and the second flat portions of the first and second casing halves each have a length ranging from 0.1 inches to 3 inches. 
     
     
         10 . The steam turbine of  claim 1 , wherein the inner surfaces of the first casing half and the second casing half form a substantially oval-shaped cross section. 
     
     
         11 . A steam turbine, comprising:
 a casing defining an interior cavity,   wherein the casing comprises a first casing half and a second casing half, which are connected to one another to form the casing, and   wherein the first and second casing halves each have an inner surface comprising at least one flat portion and a substantially curved portion.   
     
     
         12 . The steam turbine of  claim 11 , wherein the first casing half and the second casing half are connected at a split line. 
     
     
         13 . The steam turbine of  claim 11 , wherein the first casing half and the second casing half are mechanically connected to one another. 
     
     
         14 . The steam turbine of  claim 12 , wherein, at the split line, an internal pressure causes flat edges of each of the first casing half and the second casing half to rotate towards one another to create a seal. 
     
     
         15 . The steam turbine of  claim 11 , wherein the first and second casing halves are separable from one another when not connected to one another. 
     
     
         16 . The steam turbine of  claim 11 , wherein the at least one flat portion of the first and second casing halves comprises a first flat portion and a second flat portion. 
     
     
         17 . The steam turbine of  claim 16 , wherein the substantially curved portion of the first and second casing halves is positioned between the first flat portion and the second flat portion. 
     
     
         18 . The steam turbine of  claim 16 , wherein the first flat portions and the second flat portions of the first and second casing halves each have a length ranging from 0.1 inches to 3 inches. 
     
     
         19 . The steam turbine of  claim 11 , wherein the inner surfaces of the first casing half and the second casing half form a substantially oval-shaped cross section. 
     
     
         20 . The steam turbine of  claim 11 , wherein the inner surfaces of the first and second casing halves have corresponding shapes.